Reduction drive mechanism with power feedback



July 26,1949. S.G..GUIINS 2,477,451

REDUCTION DRIVE MECHANISM WITH POWER FEED-BACK Filed 0013., 16, 1945//VPl/ 7' INVENTOR ATTORNEYS Jagger" (min:

Patented July 26, 1949 M on fifiMWi'ffi POWER FEEDBACK :Sergei Gums-,-Stafnford,-* 901111 ,assigno'r to The @Aomtorque fiompany, Stamford,Conn., a

poiation of Gonnectiut attiitaiin paste 16, 194 s,- semt-I-Noltit-2:511-

i This invention relates tea driving nieenemsm, particularly to ahelicopter ante, and has her an object to provide a hydromechanic'altransmission adapted for controlling thesp'ed'of the mainrotor oft-a helicopter "without substantial dissipationof energy.

Another object of the inventionfis to' provide an improved hydromedhahitial power splitting arrangement for controlling the speedofa'helicopter.

A further object of the' inyentiohis to provide an improvedhydro=mechanioal "arrangement for controlling the speed ofa helicopterwithout substantial loss of energy.

Yet a further'objc'tof the invent vide an improved hydro=medhanical owertransmission capable of varying mean-gum veloeity ratio between-theinput and output iner'nbers,

A still further object of the inventionisto provide an improved drivein'which the di ivin'g" shaft is driven at constantspeed whilethe'drivenshaft is maintainedat preselected speeds.

With the above objects in vrewtene em-bodiment of the inventiondiscloses afp tion of *a helicopter driving mechanism i which the "inputand output shafts are interconnectedby a double planetary gear -trairihairlfig the cage-ti one planetary train fixedly teutiea te the sun gearof thesecond planetary train 'anatneag'e of the second planetary train'fixdly'coupledfto the output shaft, the sun r'gear' of the firstplanetary train being rigidly connected to the input shaft. For varyingthe 'out'put shaft s'peed,-the ring gear of the first planetarytrainisooupled through a reduction gear traintovariable hyt draulictransmission comprising a fixed hydraulic unit and a variable hydraulic"unit-the" lattr unit of which is aIsogeared-to thelnputshaft. Byvarying the stroke-of the. variable hydraulicunit, the movement impartedto the ring gearof the first planetary train may be variedp-so that thespeed of the output shaft is correspondingly varied. In other words atpredeterminedstroke settings (except zero strokeyof thetriablehydraulicunit thefirst planetary-rmg:gear will be rotated by the inputShaftq-atpredetermined speeds todrive the fixed-hydraulie unit as'a pump, therebyconverting reduotion in voutput shaft speed to torque, Thepumpyin'tu-rn;drives the variable hydraulicyunit as a motor; which delivers theotherwise wastewpower to the input shaft.

, m r r qm le s; under n n -tit e ven- Ation"will be obta ed om-the'rietaileddescrtpusewmehiranotsand:tyeeereeeetathe e 55 t8 by'varyingtl'ld speed-f rotation erwtne p t is topm- F pended drawing which "showsa view .ipar-tl-y an section "df a variable transmission interconnecting the input and output i'shaft's or a 'a helicopter drive.

Referring now to the drawing, there iis shown an input or driving shaftIll"coupledlinvany suit ablewmanner to a power source or prime-' mover(not shown), such as an'intrnal combustion en gine, which maybeiadapte'd te i-mparta lionstant speed thereto. The driving shaft 10,-which'r is shown with an axial opening 3H,-

:rotatably mounted in 'anti-driction bearings l2, H "1811;- ably securedto a-housing 16 '(shown'schemati- :cally). Adjacent the inner end of thedriving shaft Ill is rigidly connected aminputorsun gear 18 of an inputplanetary gear train comprising a plurality of planetary-pinions 20(only gene of which is shown) in mesh engagement with gear [8 androtatably mounted on antipfriction bearings 22, supported in turnby aplanet arrier or cage 24 adapted for orbital movement around drivingshaft I0. Planetary pinionsill. also mesh with internal teeth of aninput.rinlgear 26, whioh is "supported in housing [6 by anti-frictionbearings 21.

Input cage 24 is'rigldIys'ecu "eu 'a 'sw gear '23 of anoutputpl'arietai'y g'en rgm by 'a blt nut assembly '30, the gear 28'being in enga ement Witha morality" of 'dllltplitfi lahfilfi pinions 32rotatably mounted on anti-friction bearings 34, which are supported bya'carnertr cage 36, in turn spliiied to ahollowidrivenishaft 38, whichis adapted to drive the main rotor (not shown) of a helicopter. Aportion "ofr'shaft"38 fi's shown mounted on anti i'i'ic'tionbe'arings Mlsiiitably supported by housing It. 'Tfie'piiiiohstrafe shown in meshengagement "'ith "exterfialgteeth of an output ring gear 42 ,fwhich'inaybefiixedl'i siired to, er integral "withfithe housing i 6; oil-seal 441sshdwnlntr'posd btwen'tl'ie ant mg and driven shafts to;sim specnveiy.

Froin the) above it is' radiIy seen that mouen is transmitted from thedriving shaft lfl tothe driven shaft 38 through the input pianetsrygesrtrain comprising gear IBI'planetaryfpiniIins 2U, cage 24, and outputpla'ntary af train -ct$i=ii= prising'sun gear 28 rigidly coupled toinput ease i l, planetary pinion 32, ease 3E splix'ie'd to the drivenshaft 38. Iii other wordsniovement is transmitted from the driv e shaftto the driven sha'ft'by means of a two stae plantaryfig'ai train; Withthe output-r'ing gear nz a ways x'ea as a'stationaryreatiiimithasheretofore towarywtheii'speed of ring gear 26. Thus, with ring gear 26stationary the output shaft 38 will rotate at a predetermined or basicrate of speed, While with the input ring gear rotating in one directionthe output shaft speed will be reduced below the basic speed. With theinput ring gear rotating in the opposite direction the shafts speed willbe-raise'd above the basic speed. However, the above variations inoutput shaft speed were accomplished with total loss of the power notutilized by the output shaft, particularly at reductions in outputspeed.

Therefore, in order to utilize the torque or energy that would otherwiseb lost during reductions in speed of the output shaft, applicantinterposes between the input ring gear 26 and the input shaft H] avariable hydraulic transmission comprising a fixed hydraulic unit 46 anda variable hydraulic unit 46 interconnected by a pair of conduits 50 forpassage of liquid therethrough. The transmission, including hydraulicunits 46, 48,- may be. of .any suitable type, such as that disclosed inOrshansky Patent 2,256,324 of September 16, 1941, and inasmuch as itsprinciple'of operation is well-known, it is considered that adescription thereof is unnecessary, especially since the transmissionper se does not form a part of the present invention. It is, of course,understood that the positions of the fixed and variable fhydraulie units46, 48, respectively, may be reversed, and also that both units, ifnecessary, may be of 'a variable nature.

To 'increase the sensitivity of the hydraulic transmission areductiongear train having a ratio :of about 30 to 1 is interposedbetween the input :ring gear 25 and the fixed hydraulic unit 46. Thespeed ratio, of course, may be of any other suitable figure and is notto be understood as limited to this amount. Ring gear 26 is,thereforef'provided with external teeth 52, which are shown inmesh'engagement with external teeth 54 of a ring gear 56, which is alsoprovided with internal teeth 58. Ring gear 56 is rotatab lysupported inhousing It upon anti-friction bearings 60.

A pinion 62, which is fixedly mounted upon a spindle 34, meshes with theinternal teeth 58 of ring gear 56, spindle 64 being rotatably supportedupon anti-friction bearings 66, 68 secured to a carrier or cage'ldwhich, in turn, is rotatably supported upon anti-friction bearingsI2, 14 securedto the housing I5. A second pinion '16 is also fixedlyfastened to spindle 64 and this pinion is adapted, as shown, to meshwith the stationary ring gearv l1 integral with or connected totheoutput ring gear 42, thereby imparting orbital movement to the cage lupon rotation of pinion 62. 'Cage It may-be secured to a shaft 18 of thefixed hydraulic unit 46 in any suitable manner, such as by a splinedconnection. It is thus apparent that with a speed ratio of 30 to 1 thefixed hydraulic unit shaft l6 may-be rotated at 3,000 R. P. M., whilethe input ring gear 26' is rotated at 100R.P.1Vi. I Referring to thevariable hydraulic unit 48, a shaft 86 thereof having a clutch 82 isrigidly coupled to a rotatable sleeve 64 mounted upon anti-frictionbearings 66, 88 secured to housing l6. Sleeve 84 is shown splinedinternally to one end of a shaft 96, which is journalled within thesleeve bore and which has as its outer end abevelled gear 62 for meshengagement with another bevelled gear 94 splined to the input or drivingshaft l6. Shaft 96 is also supported upon anti- ;friction bearing 88. itis readily apparent that shaft 80 of the variable hydraulic unit 48 willrotate continually with the driving shaft I6.

In operation, assuming that the variable hydraulic unit 48 is set atzero stroke, the shaft 86 of this unit will rotate freely with the inputshaft I0 but no liquid will flow through the conduits 50 connecting thisunit with the'fixed hydraulic unit 46, in View of the zero strokesetting. The fixed unit 46 will be in what is known as a hydraulic lockcondition. Fixed unit shaft 18 cannot rotate and therefore input ringgear 26 remains stationary. Accordingly, the speed and torque of thedriving or input shaft [0 will be transmitted via the sun gear i 8 tothe planetary pinion 20, which revolves orbitally' about the stationaryring gear 26 and causes cage 24 of the input planetary train to rotatethe sun gear 28 and pinions 32, which in turn cause cage 36 of theoutput planetary train to drive the output shaft 38 at the predeterminedbasic speed. Under this assumption of zero stroke of the variable unit48, there is no utilization of torque from the ring gear 26, there beingno power splitting at this basic speed.

However, assume next that the main rotor shaft 38 is to be driven at aspeed lower than the basic speed. Under this assumption the stroke ofthe variable hydraulic unit 48 will be set to correspend with therequired output speed, whereupon liquid will be permitted to flowthrough the conduits 56. Accordingly, the power transmitted by thedriving shaft l6 will be split into two paths, one path being tracedthrough the double planetary train to the output shaft, as describedhereinbefore, and the other path through the sun gear l8 and planetarypinions 26 to the ring gear 26 which rotates or, as it may be termed,sli s therewith to rotate ring gear 56, pinions 62, cage 10 and shaftfltwhich drives the fixed hydraulic unit 46 as a pump. Circulation ofliquid through the conduits 56 drives the variable hydraulic unit 48 asa motor, which feeds back a predetermined amount of torque or energy,dependent upon the stroke setting, to the input shaft [6 through thebevelled gears 92, 94. This feed-back torque is normally wasted inconventional helicopter drives By reversing the stroke setting of thevariable hydraulicunit 48,the functions of the two hydraulic units'dfi,48 may be reversed to increase the output speed of the shaft 38, thatis, fixed hydraulic unit46 may be operated as a motor while variablehydraulic unit 48 is operated as a pump. In this instance, a portion ofthe power from the driving shaft It will be diverted at the bevelledgears 94, 92 to drive the variable hydraulic unit'48 via shaft 80, themain portion of the input power passing through the double planetarytrain to the'output shaft. Liquid flow through conduits" 50, developedby the variable hydraulic unit 48, drives the fixed hydraulic unit as amotor which, in turn, through the reduction gear train causes ring gear2-6 to rotate in a direction opposite to that described hereinbefore,thereby increasing the rotation of cage 241and correspondingly, that ofthe output shaft 38,

It is thus seen that advantages are obtained over theconvention'alhelicopter drive by adaptationof applicant's invention to not onlyutilize the hitherto waste of power but also to provide an improvedarrangement for varying the speed of the main rotor. While the preferredembodiment discloses a double planetary gear train interconnectin thedriving and driven shafts, a single planetary gear train may be utilizedinstead, ,inwhich the sun gear and planet carrier maybe rigidly coupledto the driving and driven shafts, respectively, and the ring gearcoupled the invention, as defined in the appended claim.

For example, the features of this invention may also be applied tomachine tools, ships, land vehicles, and any other devices where it isdesired to vary the speed ratio.

I claim:

In a driving mechanism for varying the speed of the main rotor of ahelicopter, the combination with a driving and driven shaft therefor ofa first stage and a second stage planetary gear train respectivelyconnected to said driving and driven shafts, said first stage trainincluding a sun gear rigidly connected to said driving shaft, a,planetary pinion in mesh with said sun gear, a rotatable ring gear inmesh with said planetary pinion, and a revolvable cage for carrying saidplanetary pinion, said second stage planetary gear train including a sungear rigidly coupled to said cage, a planetary pinion in mesh with saidsecond stage sun gear, a stationary ring gear in mesh with said secondstage planetary pinion, and a cage for carrying said second stageplanetary pinion, said cage being rigidly coupled to said driven shaft,and hydro-mechanical means interposed between said ring gearsand saiddriving shaft for varying the speed of said driven shaft, said meanscomprising a third ring gear;

in mesh with said rotatable ring gear, a third pinion in mesh with saidthird ring gear, a fourth pinion rigidly coupled to said third pinionand in mesh with said stationary ring gear, a third cage for carryingsaid third'and fourth pinions, a variable hydraulic transmission rigidlyconnected to said third cage, and gear means for interconnecting saidtransmission with said driving shaft, whereby at decreased speed of thedriven shaft energy derived from the driven shaft is fed back into thedriving shaft and at increased speed energy derived from the drivingshaft is fed into the driven shaft.

SERGEI G. GUINS.

REFERENCES CITED The following references are of'record in the file ofthis patent:

UNITED sra'ra's PA'IENTQ

